Soft tissue flaps are used in reconstructive surgery in a variety of indications to correct a multitude of tissue defects. For example, flaps may be used to resurface a variety of wounds about the head, neck, extremities and trunk or they may be employed to cover exposed tendons, bones or major blood vessels. Flaps may be used about the face where color match and contour are important or they may be used to close wounds having a poor blood supply as where wound circulation would not support a skin graft. A flap traditionally refers to skin and subcutaneous tissue (or muscle, bone or other tissue) along with the entire vascular plexuses thus bringing a large supply of tissue and an intact blood supply to the site of injury. Modern surgical techniques have expanded the traditional definition of a flap to encompass free, microvascular flaps which may be anastomosed to an existing blood supply at or near the site of injury.
A persistent problem in the use of soft tissue flaps has been that of survival of the flap due to a diminished blood supply thus leading to a failure of the flap and a consequent unsatisfactory management of the wound. Various factors which influence the failure of these soft tissue flaps include extrinsic factors such as compression or tension on the flap, kinking of the pedicle, infection, hematoma, vascular disease, hypotension and abnormal nutritional states. Ischemia has also been postulated as playing a role in skin flap failure although the precise etiology has not been conclusively elucidated. For example, Reinisch (Plastic and Reconstructive Surgery, Vol. 54, pp 585-598, 1984) theorizes that the ischemia is due to the opening of A-V shunts with resultant non-nutritive blood flow to the effected area. On the other hand, Kerrigan (Plastic and Reconstructive Surgery, Vol. 72, pp 766-774, 1983) speculates that the ischemia is due to arterial insufficiency causing insignificant blood flow in the distal portion of the flap.
Because failure of these flaps can have deleterious consequences for the patient, various measures have been taken in the past to attempt to salvage failing flaps. Such measures include re-positioning the flap, topical cooling of the region, hyperbaric oxygen as well as the administration of various drugs. Among the drugs which have been used are dimethyl sulfoxide, histamine, isoxuprine and prostaglandin inhibitors. Additionally, various sympatholytic agents such as reserpine, phenoxybenzamine, propranolol guanethidine and 6-hydroxy-dopa have been used, as well as rheologic-altering agents such as dextran, heparin and pentoxifylline. Systemic steroids have been used in an attempt to increase body tolerance to ischemia, as has topical applications of flamazine. However, none of the treatment modalities or drugs used in prior attempts to reduce soft tissue flap necrosis have been entirely satisfactory or met with widespread acceptance in the medical community. Hence a need still exists for a means of reducing soft tissue flap necrosis (and the resultant failure of the flap) for use in reconstructive surgery.